High-Spermidine-Producing Yeast Strain for Autophagy-Promoting Applications

Polyamines, particularly spermidine, have emerged as key dietary factors with roles in cellular health, autophagy, and longevity. However, strategies for scalable production of polyamine-rich food ingredients remain limited. Here, we report the development of a high-spermidine-producing Saccharomyces cerevisiae strain, 3L63, obtained via ultraviolet mutagenesis of the K7 strain. This strain exhibited a 5.9-fold increase in the total polyamine content, with spermidine being the most abundant. A scalable fermentation system of up to 10⁴ L was established, yielding a dried yeast product that met food safety criteria. Whole-genome sequencing identified mutations in central metabolic pathways, including ARG3, and functional enrichment analysis suggested broad metabolic rewiring, supporting an enhanced biosynthetic capacity, including polyamines. Free amino acid profiling revealed higher arginine levels in 3L63 than in K7, which is consistent with its role as a polyamine precursor. The 3L63 yeast-derived product was enriched in essential amino acids and polyamines. Functionally, this strain promoted the proliferation of normal and senescent human dermal fibroblasts, and its autophagy-inducing activity exceeded that of equivalent concentrations of pure spermidine, suggesting synergistic effects of yeast-derived bioactive compounds. This study demonstrates a non-genetically modified, high-spermidine yeast strain as a promising functional food ingredient with potential applications in healthy aging.